Lift bridge



Dec. 15, 1925- 1,565,571

E. E. HOWARD ET AL LIFT BRIDGE Filed Feb. 2, 1925 2 sheets-sheet 1 l K I i 1 :1 E 11v V5 1 Q [ma 15M:

ATIOM Dec.15,1925. 1.565.571

E. E. HOWARD-ET AL LIFT BRIDGE Filed Feb. 2, 1925 2 Sheets-Sheet 2 Patented Dec, 15, 1925.

UNITED smras 1,565,571. 1 PATENT OFFICE.

ERNEST E. HOWARD AND HENRY C. TAMMEN, OF KANSAS CITY, MISSOURI, ASSIGNORS TO HARRINGTON, HOWARD & ASH, A COPARTNERSHIP CON SISTING OF JOHN LYLE HARRINGTON, ERNESTE. HOWARD, AND LOUIS R. ASH.

LIFT BRIDGE.

Application filed February 2, 1925. Serial No. 6,159.

To all whom it may concern:

Be it known that we, ERNEs'r E. HOWARD and HENRY C. TAMMEN, citizens of the United States, residing at Kansas City, in the county ofJackson and State of Missouri, have invented certain new and useful Improvements in Lift Bridges; and we do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the figures of reference marked thereon, which form a part of this application.

This invention relates to lift bridges and the primary object thereof is to provide a lift bridge so constructed that the span between two towers may be raised and lowered with a minimum expenditure of power and it is also the object of the invention to simplify the construction of the lift bridge to reduce weights of counterweights and to reduce loads on tower piers below those needed in ordinary lift spans.

The span is suspended from the towers at its respective ends by tackles, each employing a sheave or pulley or pulleys attached to the movable span and supporting the weight thereof. The tackle employs a wire rope, one end of which is fixed to the tower near its top. The wire rope passes under the pulley or pulleys attached to the movable span,

thence over one or more sheaves or pulleys on the top of the towers, thence down with the free end of the wire rope connected to a counter-poised weight about one-fourth of the span weight so that the span and counterpoise weights will be in equilibrium. The bridge span is raised and lowered by power applied to that pulley of each tackle which is attached to the span, the friction of the pulley on the wire rope being sufficient to overcome the equi-poised condition so that the bridge span may be raised or lowered under the control of an operator.

The novel construction, of the invention will be specifically described hereinafter,

reference being had to the accompanying drawings, in which- Fig. l is a side elevational view of a lift bridge constructed in accordance with our invention, and

Fig. 2 is a plan view of thebridge showing the operating mechanism.

The towers 1 and 2 may be of usual. construction and'we have shown pulleys 3 and 4 on the top of the tower 1 and similar pulleys 5 and 6 on the top of the tower 2. The

pulleys 3 and 4 for tower 1 and pulleys 5 and 6 for tower 2 support wire ropes -7 and 8 respectively, one end of each wire rope being fastened to the tower as at 9 or 10 as the case may be, so that the wireropes form loops 11 and 12 supporting pulleys 13 and 14 and 13 and 14 which are in fixed bearings attached to'the span 15, which is to be raised and lowered. Y

The wire ropes 7 and 8 have free ends 16 and 17 to which are fastened counter-poises or weights '18 and 19. each noise being approximately one-fourth the weight of the span 15 and since the span is suspended from the loops 11 and 12, it will be obvious that the span. and the counterpoises are in equilibrium unless the equilibrium is disturbed by power applied to the cables.

We have found that the frictional contact of the pulleys 13 and 14 with the cables 7 and 8 is suflicient to overcome the tendency of the weights and span to remain in equilibrium,'so we have provided means for driving the pulleys 13 and 14 and 13 and 14, there being a pulley and counter-poise arrangement at each corner of the span, but all of the counter-poise arrangements are alike and attention is called to the fact that in actual practice, more than a single wire rope 7 or 8 will be employed for each counter-poise and for that reason the pulleys are shown as provided with a plurality of grooves because a number of wire ropes will be employed at each corner, for example, about eight, although obviously the number may be varied.

The driving mechanism consists of a motor or engine 20 which may be located at some suitable point on the span. The motor is shown as driving a reduction gearing 21 through which the longitudinal shaft 22 is turned, the shaft 22 carrying pinions 23 and 24 which drive gears 25 and 26 on the transverse shafts 27 and 28, the shafts 27 and 28 carrying spur pinions 29, 30, 31 and 32, which in turn drive spur gears 33, 34, 3.5 and .36 on the pulleys 13, 14, 13 and 14. The

' friction of the pulleys on the Wire ropes will be suflicient to cause the weights 18 and 19 to raise and lower, so as to shorten or lengthen the loops 11 and 12 so as to raise or lower the span.

We are aware that lift bridges have been in general use prior to our invention but we are not aware that prior to our invention a tackle with pulleys attached to the lift span which support said span and with the power communicated to such pulleys and arrangement by which the total weight of the counter-poise weights is approximately onehalf of the lift span weight, have been employed- It is to be understoodthat the wire rope may be the standard wire. cable of commerce.

What we claim and desire to secure by LettersPatent is: M i

. 1. A lift, bridge comprising towers, a movable lift span between thetowers, tackles carried by theqtowers for supporting the movable span, the tackles including pulleys attached to the movable span, counterbalance weights, and cables supporting the weights, said cables passing over the towers andaround the pulleys, the combined weight of the counter-balance weights being not in excess of one-half the weight of the span and operating-mechanism; on the span for rotating the pulleys carried thereby.

y 2. A lift bridge comprising .towers, a movable lift span between the towers, pulleys on the towers, pulleys on the span, cables passing around the pulleys on the span and over the pulleys on the towers for suspending the span, and operating mechanism on the span for rotating the pulleys carried thereby.

3. A lift bridge comprising towers and a span between them, flexible suspension members carried by the towers supporting pulleys around which the flexible suspension members pass, the'pulleys being attached to the span, counter-balance weights associated with the flexible members, and means for driving the loose pulleys.

l. A tackle comprising a support, a cable having one end fastened to the support, fixed pulleys over which the other end passes, counter-balance weights on the loose ends of the cables, a load-supporting pulley loosely carried by the cable, and means for positively rotating the loose pulley.

5. A lift bridge comprising towers, a span between the towers, a looped tackle carried by the towers, one for each corner of the span, each tackle comprising a looped cable having a counter-poise secured to one end thereof, the other end of the cable. being secured to one of the towers, a spanesupporting pulley at each corner of the span and supported by the loop of its particular tackle, and means for positively driving said pulleys. p

6. A lift bridge comprising towers, a span between the towers, a looped tackle carried by the towers, one for each-corner of the span, each tackle comprising a looped cable having a counter-poise secured to one end thereof, the other end of the cablebeingsecured to one of the towers, a span supporting pulley at each corner of the span and supported by the loop of its particular tackle, and means for positively driving said pulleys in synchronism. o

In testimony whereof we affiX our signatures.

ERNEST E. HOWARD. -HENRY G. TAMMEN. 

